This invention concerns refrigerators and more particularly refrigerator cabinet warming heater installations. It is common practice in modern refrigerator designs to include cabinet heating devices to warm those portions of the refrigerator cabinet which are subject to formation of condensate or sweat on the exterior surfaces due to the cabinet surface being chilled below the dew point of the ambient air. These cabinet portions include the refrigerator outer case surfaces in the region of the reentrant flange of the outer steel case, since the reentrant flange which extends inwardly to join the liner or the breaker strip creates relatively high thermal conduction at this point. The high efficiency insulation found in modern refrigerators also allows relatively thin cabinet wall thicknesses, aggravating this problem.
Accordingly, it has been found necessary to provide auxiliary heaters to prevent this condensate formation.
The typical approach involves the installation of resistance heater wires extending within the outer case adjacent the reentrant flange at the point where it meets the steel outer case if the cabinet design is such as to use a breaker strip. Or, if a plastic liner construction is used, at the region where the flange of the plastic liner abuts the inside walls of the steel outer case. Many refrigerator cabinets utilize foamed-in cabinet insulation and in these designs commonly the heater element is encased within the foamed insulation. Electrical heaters are of course subject to occasional failure and these above-described designs create considerable difficulties in the repair of such units.
Firstly, the disassembly of the cabinet presents considerable difficulties in the removal of the breaker strips and other cabinetry components and the removal of the foamed-in heater element is next to impossible.
In order to overcome these difficulties, sometimes a redundant heater element is installed together with one connected to the refrigerator wiring and in the event the connected heater fails, a field repairman may merely connect the redundant heater. If the redundant heater fails, the problem of replacing it must then be faced. In addition, the use of two heater cables obviously increases the manufacturing costs of the refrigerator.
A second approach has involved the foaming-in of a heater tube within the case, which allows the heating cable to be removed and a replacement heating element snaked into the tube. However, some cabinet configurations preclude this approach and even with those cabinets which allow this repair procedure to be carried out, it is a relatively difficult process. There are situations therefore in which the only practical alternative is the scrapping of the unit which obviously is to be avoided if it is at all possible.
In certain situations with very high humidity atmospheric conditions, cabinet sweating may still occur even though the cabinet case heater is functioning properly. In those relatively exceptional situations, it would be advantageous to be able to modify the refrigerator cabinet heating arrangement in the field so as to correct the cabinet sweating. However, cabinet designs as described are such that disassembly of the cabinet components is difficult and the installation of a supplemental heat device would be difficult due to the presence of foamed insulation completely occupying the interior spaces.
It is accordingly an object of the present invention to provide a refrigerator cabinet heater installation which may be installed in the field to replace heaters which are originally installed within the interior of the refrigerator outer case which does not require disassembly of the cabinet or removal of the heating element from the foamed-in insulation.
It is yet another object of the present invention to provide a refrigerator cabinet casing heating installation which may be installed to supplement the casing heating arrangement included in the design as manufactured to correct chronic cabinet sweating in high humidity conditions.